Star Trek: Federation Propulsion Technology

Written: 1998.08.01 Last Revised: 1999.10.06

The impulse engines (red) and warp nacelles (blue) of the
Enterprise-E

Impulse Drive

Impulse drive uses a fusion-powered low-level variant of warp
drive to power the ship forward. This allows it to achieve high
relativistic speeds in excess of 0.75c (TM pg. 75) although such
speeds are normally not used and the TM suggests that combat
incidents always occur at low sublight relative velocities. This is
supported by the various onscreen combat incidents in the Star Trek
canon- we never see any combat in Star Trek where the relative
velocities of the combating ships are high (and by "high"
I mean "relativistic", rather than fighter-plane speeds).

There is some debate as to whether Federation impulse drives must
accelerate a starship in conventional space physics fashion, as
opposed to simply initiating the space warpage that allows them to
reach high relativistic speeds and bypassing the normal acceleration
curve requirements. However, the original TNG TM explicitly stated
that the old Ambassador class's acceleration was at least 10 km/s²,
and the new DS9 TM explicitly states that Bajoran impulse fighters
are limited to 15,600 m/s acceleration (this is curious, since the
units of acceleration are m/s² rather than m/s, but we can
assume that when they say "maximum delta-v" they are
actually referring to "maximum delta-v per second").
Impulse fighters can easily outmaneuver capital ships (as seen in
"Sacrifice of Angels"), so this allows us to determine
that capital ship acceleration is between 10 km/s² and 15
km/s².

The presence of a maximum acceleration limit indicates that
impulse drives do require a finite amount of time to accelerate.
Some Federation cultists have claimed that this is untrue because
the helmsman announces that they are at full impulse almost
immediately after the captain orders it, but that only indicates
that their engines are at full power. It does not indicate any sort
of speed. If the helmsman announced "we are at 0.8c"
instead of "we are at full impulse" we might have some
idea of its actual speed. But since the helmsman invariably states
"we are at full impulse" we only know that the engines are
at full power. No speed or acceleration information can be derived
from this sort of incident. In conclusion, Federation capital-ship
impulse drives appear to be capable of producing accelerations in
excess of 1,000g but less than 1,500g.

The stated highly relativistic speeds of Federation starships are
at odds with their slow observed speeds in planetary orbit, as seen
in STG, "Way of the Warrior", "A Call to Arms",
"Tears of the Prophets", and others. In all of those
situations, higher speeds would have been useful, but for some
reason, they were apparently unavailable. It is therefore surmised
that their low-level warp drive, or so-called "mass-lightening
effect" must suffer from reduced effectiveness in a planetary
gravity well. This is logical because the use of "mass-lightening"
technology in a planetary gravity well presents serious Conservation
of Energy problems. These problems are briefly discussed in the SW
Myths page. The problems with mass-lightening in a gravity well
are consistent with the invariably slow speed of starships
attempting to enter or leave orbit, although it would theoretically
be possible to very quickly circumnavigate a fixed-altitude orbit
without running into this problem because no change in gravitational
potential energy would occur.

Thrusters

Thrusters use conventional action/reaction physics to drive a
ship forward. They do not produce the speed or acceleration of
impulse drives, but they appear to be used for combat maneuvering
and docking maneuvers. It is possible that impulse drive doesn't
allow sufficiently fast direction changes to be used alone in combat
maneuvers. They appear to offer precision and flexibility of
movement unavailable with the impulse engines- for instance, angled
thrusters could theoretically rotate the ship about any chosen axis,
which would be virtually impossible to accomplish with impulse
engines.

Warp Drive

Warp drive uses a
matter/antimatter-powered space-time continuum distortion process to
drive a ship forward at many times the speed of light. The warp
speed table is as follows (taken from the TNG TM and the Star Trek
Encyclopedia):

Warp Factor

Speed in multiples of c

1

1

2

10

3

39

4

102

5

214

6

392

7

656

8

1024

9

1516

9.6

1909

9.9

3053

9.99

7912

9.9997

200,000

The TM indicates that the propagation rate of subspace
transmissions is "about sixty times faster than the fastest
starship, either existing or predicted", and we know that Warp
8 is the highest warp factor that can be maintained for long
cruising durations. Therefore, a ship attempting to cross a 120,000
light-year wide galaxy would have to be ready for a 117-year
journey, to go from end to end. By dividing the speed of subspace by
sixty, we find that the maximum speed of any starship is
roughly 3333c. This is consistent with the pilot of Star Trek:
Voyager where Captain Janeway said the Voyager would take 75 years
to cover the 70,000 light year distance back to the Alpha Quadrant
"at maximum warp."

It is noteworthy that in ST5, the Enterprise-A
apparently traveled to the galactic core over a fairly short time
duration (a few hours, or a few days). This would be a trip of many
tens of thousands of light years, which would seem to suggest that
the warp drive speed of the Enterprise-A is comparable to an
Imperial warship using hyperdrive. However, this interpreted travel
speed is completely inconsistent with every single episode of
Voyager (which wouldn't even exist as a series if it weren't for the
speed limitations of warp drive). Some Federation cultists have
chosen to simply assume that ST5 is indicative of true warp speed,
and that every other incident of poor speed is due to an anomalous
condition. However, this is obviously a ludicrous assumption: if one
incident contradicts literally hundreds of other incidents,
then the one incident must be the anomaly. However, it still
must be explained. There are a few possible explanations:

Sybok knew of a wormhole that led
to the galactic core from near their starting location. This
wormhole must have been unstable, but it might have remained
stationary long enough for Sybok to pass through and for the crew
to return to Federation territory afterwards.

Sybok might have been speaking figuratively when he
said that they were headed toward the centre of the galaxy.
Coruscant is invariably described as the centre of our galaxy and
sometimes even the centre of the universe, yet it is thousands of
light years away from the physical centre of the galaxy and
extremely far from the centre of the universe. The "Great
Barrier" that he spoke of was similar to the "Great
Barrier" seen in TOS, which was actually at the outer
edge of the galaxy. In fact, the physical appearance of the planet,
and the barrier itself, indicated that it could not have
been the centre of the galaxy. The small planet in ST5 bore no
resemblance whatsoever to the massive collection of stellar matter,
nebular gases, and antimatter fountains which have been observed at
the centre of the Milky Way galaxy.

Regardless of which explanation we choose, it is clear that ST5
cannot be used as "proof" that every other film and
episode in Star Trek history is incorrect in its portrayal of warp
drive speed.

The Federation DS9 TM specifies that the maximum speed which can
be maintained for as long as 12 hours is warp 9.9 for upgraded
versions of the Galaxy-class and Nebula-class starships. Maximum
12-hour speeds are listed as warp 9.2 for the Miranda-class, warp
9.7 for the Norway-class and Saber-class, and speeds between warp
9.55 and 9.75 for various other sundry ship classes. Their fastest
starship appears to be the Defiant-class, which is rated for a
maximum of warp 9.982 for 12-hours. This represents a significant
strategic advantage over other groups in the area such as the
Romulans, Klingons, Cardassians, Jem'Hadar, etc. According to the
DS9 TM, no starship from any of those groups has been observed
exceeding warp 9.6.

Using this information, we can conclude that the average
Federation, Romulan, Klingon, Cardassian, or Jem'Hadar warship is
capable of approximately 2000c cruising speed, with high-end ships
being capable of 3000c, and a handful of exceptional vessels being
capable of roughly 6000c. This is, of course, insignificant compared
to the speed of hyperdrive which ranges into the millions or tens of
millions of times c, but it nevertheless represents a significant
improvement over previous efforts from the Federation.

Interdiction

Warp drives can be disrupted by strong gravity fields. The
gravity well of the Dyson sphere in Relics forced the
Enterprise-D out of warp, even though its surface gravity level was
no higher than Earth-normal gravity. This was seen when Starfleet
officers boarded the derelict, unpowered USS Jenolan, where they
were able to move about unimpeded even before they re-powered
the ship's systems. This indicates that the intensity of the gravity
well is not as important as its sheer size- a passing starship would
be influenced by such a large gravity well for an unusually long
duration, even though the gravity well is no more intense than a
typical planetary gravity well.

Further evidence of warp drive vulnerability to gravity wells is
seen in Once More Unto the Breach when Worf used an inverse
graviton beam (an anti-gravity beam) to keep Jem'Hadar warships from
going to warp. The technique was successful, so this indicates that
Jem'Hadar warp drives can be prevented from functioning through the
use of anti-gravity beams. It is reasonable to conclude that
Romulan, Klingon, and Federation warp drives would be similarly
affected, since all of the aforementioned warp drives appear to
function on the same basic principles.

The enormous gravity-well projectors can be reversed to project
anti-gravity beams in a manner similar to a standard Imperial
repulsorlift drive, but on a larger scale (and a much larger scale
than Worf's puny anti-graviton beam). In fact, this was actually
done in Solo Command, when an interdictor reversed its
gravity-well projectors to put a Victory-class Star Destroyer away.
This means that Imperial interdictor cruisers can potentially be
just as effective on warp-driven starships as they are on
hyperdrive-equipped starships, regardless of whether
reverse-polarity is actually required.

Conclusion

Federation propulsion technology is similar to Star Wars Imperial
propulsion technology in sublight performance, but vastly inferior
in superluminal performance. This confers a large strategic
advantage to our forces; we can move and attack star systems at
will, knowing that their forces cannot possibly intercept us or
reach the target before we do.

Acknowledgements

A mysterious cloaked figure named "Jedi Anger",
for providing the interdictor reference to Solo Command.